The present invention relates generally to lawn mowers, and more particularly to a vacuum device which automatically draws grass clippings and other solid debris into a grass catcher.
Previous lawn mowers have utilized the vacuum effect created by a rotating grass cutting blade to collect grass clippings and other solid debris within a grass catcher, thus obviating the need to rake. The rotating blade will act as an impeller to force air and solid debris into a grass catcher. Generally, the grass catcher must have rearwardly positioned vents or mesh which retain solids such as grass clippings, twigs, and leaves within the grass catcher but allows the flow of air in which the solids are entrained to pass through the grass catcher.
A problem associated with this type of system is that dust particles are capable of filtering through the mesh, thus creating a dust cloud behind the mower which is unpleasant for the operator of the mower, and which may be harmful to the mower's engine.
To alleviate this problem, a closed loop vacuum system was developed by Enters, et al. (U.S. Pat. No. 3,708,968) in which air and associated dust entering the grass catcher is returned to the mower blade through another chute, and thereby recirculated, as opposed to being discharged into the atmosphere. However, the system disclosed by Enters is complex and requires a multi-part grass catcher, inlcuding a rotating fan blade used to separate the air flow generated by the mower blade from the solids sought to be deposited within the grass catcher.
Thus, a need exists for a closed looped lawn mower vacuum system which automatically separates solids entrained in the air flow passing through the grass catcher, without discharging the air flow to the atmosphere.